Your ISP advertises a 40 megabit per second connection, but that doesn’t look anything like the download speed you see when you’re grabbing a big file. What’s the deal? Are you not getting all the bandwidth you’re paying for?

Dear How-To Geek,

The package deal I have through my local ISP is for a 40Mb connection (that’s the wording they use). When I download files I get around 4.5-5 (and definitely not 40!) Now… this doesn’t seem to be a big deal, because I can download everything I want pretty quickly, YouTube doesn’t stutter or anything, I never have to wait to load my email or web page, etc. But if I’m paying for a 40Mb connection why am I not getting a 40Mb connection?

Sincerely,

Bandwidth Confused

This is a fun question because it allows us to discuss and clear up a common misconception, and learn a little bit about computer history along the way.

Let’s start by delving back into the history of computer networks. Data transfer over networks has always been measured in bits. A bit is the smallest and most basic unit of measurement in computing and digital communications. Bits are most commonly represented in the binary system, via 0 and 1. Bit, in fact, is a contraction of the the longer phrase “Binary Digit”.

The speed of a network is denoted using a bit-per-second notation. Originally, networks were so slow that their speed was measured in just bits, but as network speeds increased, we started measuring internet speed in kilobits per second (remember 56k modems? That meant 56 kilobits per second), and now, megabits per second.

Now, here’s where things get confusing for the average non-geeky-Joe. Computer storage is not measured in bits, it’s measured in bytes. A bit, as we’ve established, is the tiniest unit of measurement in the digital kingdom, that primordial 1 or 0. A byte, however, is a unit of digital information that (in many operating systems, including Windows) is eight bits long. Another term, used by computer scientists to avoid confusion over the different size byte structures out there in the world, is octet. In other words, the byte system that your operating system uses is a bunch of bits strung together in groups of eight.

This difference is where, on the surface, it all seems to fall apart. You see, you have a broadband connection that is capable of 40 megabits per second (under ideal conditions, 40,000,000 bits come down the line). But your operating system and all the apps on it (web browsers, download helpers, torrent clients, etc.) all measure data in megabytes, not megabits. So when you see that download chugging along at 5MB/s, that means megabytes per second–as opposed to your 40Mb/s, or megabits per second, internet package. (Note the MB vs Mb notation.)

If we divide the speed of your connection (measured in megabits) by 8, we arrive at something resembling the download speed you’re seeing in your speed tests: 40 megabits divided by 8 becomes 5 megabytes. So yes–if you’re seeing closer to 5 megabytes per second on a 40 megabit plan, you are indeed getting what you pay for (and can even pat yourself on the back because you’re getting downloads speeds consistently at the edge of what your internet package supports).

Keep in mind that not all downloads will max out your connection. Some may be much slower, not because your internet is slow, but because the server you’re downloading the file from is busy or slow.

You can back this up by heading to a site like speedtest.net, which measures your internet speed in megabits, just like your internet provider does. If Speedtest’s results match up with the internet package on your bill, you’re golden. If not, it’s probably time to contact your internet provider and see why you aren’t getting the speeds you pay for.

Have a pressing tech question? Shoot us an email at ask@howtogeek.com and we’ll do our best to answer it.

Jason Fitzpatrick is a warranty-voiding DIYer who spends his days cracking opening cases and wrestling with code so you don't have to. If it can be modded, optimized, repurposed, or torn apart for fun he's interested (and probably already at the workbench taking it apart). You can follow him on Twitter if you'd like.

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